1. Field of the Invention
The present invention relates to a manufacturing method of a liquid jet recording head used in a liquid jet recording system for performing a recording operation to a recording medium such as recording paper, etc. by discharging a recording liquid such as ink, etc. as a liquid droplet from a very small discharge port, a liquid jet recording head manufactured by this manufacturing method, and a manufacturing method of an element substrate for the liquid jet recording head. The liquid jet recording head manufactured by the present invention can be applied to a printer, a copying machine, a facsimile telegraph having a communication system, a device such as a word processor, etc. having a printer section, and a recorder for industry compositely combined with various kinds of processors, which perform a recording operation to a recorded medium such as paper, thread, fibers, cloth textile, leather, metal, plastic, glass, wood, ceramics, etc. Here, "record" in the present invention means giving an image having no meaning such as a pattern, etc. to the recorded medium as well as giving an image having a meaning such as characters, figures, etc. to the recorded medium.
2. Related Background Art
A liquid jet recording head used in a liquid jet recording system (an ink jet recording system) has a unit element and a roof plate in one typical form. In the unit element, plural discharging energy generating elements are formed on a substrate at a predetermined interval. The roof plate has plural discharge ports for discharging a recording liquid such as ink, etc. and also has plural grooves as flow paths respectively communicated with the discharge ports. The liquid jet recording head is obtained by joining the unit element and the roof plate to each other in a state in which positions of the discharging energy generating elements and the grooves as flow paths are accurately aligned with each other. This liquid jet recording head is constructed such that characters are printed to the recording medium such as recording paper, etc. by jetting the recording liquid as a droplet from the discharge ports by giving discharging energy to the recording liquid within the flow paths by the discharging energy generating elements.
In the liquid jet recording head, consistency of an increase in printing speed and an improvement of an image quality has recently been required. For example, there is an elongated liquid jet recording head as shown in FIG. 4 as a liquid jet recording head able to cope with this consistency. In the elongated liquid jet recording head of this kind, plural unit elements 100 (a first substrate) having plural discharging energy generating elements (e.g., heating elements) 101 are precisely positioned and arranged on a base plate 102 made by a material such as a metal, ceramics, etc. so that a recording element of an elongated line head is made. Plural discharge ports 106 for discharging the recording liquid and a roof plate 105 (a second substrate) are joined to each other on this recording element so that the liquid jet recording head is manufactured. The roof plate 105 has a concave portion for constituting unillustrated plural liquid flow paths communicated with the respective discharge ports 106 and an unillustrated common liquid chamber for supplying the recording liquid to each of the liquid flow paths (the liquid flow paths and the common liquid chamber are generally called "a passage"). The unit elements 100 each having plural heating elements as the discharging energy generating elements 101 are manufactured by cutting a silicon substrate formed by patterning the plural unit elements in a film forming process, etc. and separating the individual unit elements from each other. Such an elongated liquid jet recording head is a high function recording head able to realize a high definition image by increasing an arranging density of the discharging energy generating elements (heating elements) and a processing density of the grooves of the roof plate.
In a manufacturing process of this elongated liquid jet recording head, an important technique for preventing a reduction in image quality caused by a connecting stripe at a high recording density is to arrange the unit elements precisely and closely as much as possible. Cutting of the silicon substrate with high accuracy is required to obtain such high arranging accuracy.
Japanese Patent Application Laid-Open No. 2-212162 (U.S. Pat. No. 4,851,371) discloses an effective technique with respect to such a requirement of the cutting accuracy and an improvement of the arranging accuracy relative to this requirement. Namely, a problem exists in that a circuit network is cut into pieces by microscopic damage (fine damage such as chipping, cracking, etc.) caused on a chip surface at a cutting time of a silicon wafer. To solve this problem, the silicon wafer is cut by precisely inclining a cutting blade along a cutting street between the unit elements to be partially cut. Thus, this technique realizes an arranging structure in which the unit elements come in line contact with each other on the surface of a cutting portion, but are separated from each other on a bottom face of the cutting portion.
However, in the technique disclosed in the above Japanese Patent Application Laid-Open No. 2-212162, it is necessary to perform cutting for forming a face having a cut end inclined twice and processing (cutting or etching) for removing an unnecessary portion. Therefore, it is required that an arranging width (the distances in longitudinal and transversal directions between the unit elements) of the unit elements integrated within the silicon wafer is secured to a certain extent. Further, it is very difficult to prevent the damage of the chip surface from reaching a circuit pattern when no thin blade is used as the used cutting blade even when these distances can be secured by setting the arranging width to be narrow. In the cutting using the thin cutting blade, dispersion tolerance of a cutting width is large as described in the above publication. To remove this dispersion tolerance, it is necessary to smooth (precut, dressing, etc.) a resin adhesive blade considerable times. Therefore, when a large number of unit elements are produced by cutting, it is anticipated that a time required to process one product is considerably increased. It is necessary to rotate the heating element wafer 180 degrees to make a pair of inclined cut ends oppositely directed to each other. However, considerable high accuracy is also required with respect to this rotation.